1. Field of the Invention
This invention relates to an office machine, and more particularly to a scanning device that includes a fastening unit for fastening a sensing unit to a scanner body.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional scanning device includes a scanner body 1, a scanning unit 2 disposed in the scanner body 1, a lens unit 3 disposed in the body 1, and a sensing unit 4 aligned with the lens unit 3. The scanner body 1 has a housing wall 102 defining a space 101. The housing wall 102 has a first opening 103 formed in a top portion thereof, and a second opening 104 formed in a lateral side thereof. The scanning unit 2 includes two light-emitting members 201 disposed in the first opening 103, and a plurality of reflectors 202 disposed in the space 101 for reflecting light beams emitted from the light-emitting members 201. The lens unit 3 is disposed in the second opening 104 for receiving reflected light beams from the reflectors 202. The sensing unit 4 includes a circuit board 401 attached to the scanner body 1 for covering the second opening 104, and a sensor 402 disposed fixedly on the circuit board 401. The sensor 402 may be a charge coupled device (CCD) image sensor or a complimentary oxide semiconductor (CMOS) image sensor for receiving an optical signal from the lens unit 3 and outputting a corresponding analog signal.
When light beams are emitted from the light-emitting members 201 onto an object (S) to be scanned, which is placed on a sheet of glass (P), reflected light beams are guided onto the lens unit 3 by the reflectors 202. Hence, the sensor 402 receives optical signals from the lens unit 3 to thereby output analog signals corresponding to the optical signals.
To assemble the sensor 402 onto the scanner body 1, a plurality of internal thread members 105 are pre-embedded into the scanner body 1. An outer surface of each of the internal thread members 105 has an anchoring portion 106. A plurality of bolts 403 extend respectively through holes 404 in the circuit board 401, and engage respectively the internal thread members 105. As such, the sensing unit 4 is fastened to the scanner body 1.
The aforesaid conventional scanning device suffers from the following advantages:                (1) When a distal end of any of the internal thread members 105 projects from an outer surface 107 of the scanner body 1, or when a threaded hole in any of the internal thread members 105 is deflected from the corresponding hole 404 in the circuit board 401, the circuit board 401 may be displaced slightly from its originally intended position such that the sensor 402 may be unable to receive fully the optical signals from the lens unit 3. This affects adversely the scanning effect of the scanning device.        (2) When the internal thread members 105 are assembled onto the scanner body 1, improper operation may result in damage to the anchoring portions 106. As such, the internal thread members 105 need to be replaced. However, such replacement is difficult, time-consuming, and expensive.        